I love this soup so much, I probably make it far too often. Before I met my husband I was a pretty strict vegetarian and the only meat product I really missed was French onion soup. I tried it with every broth imaginable and it just wasn’t the same. About a year ago a friend told me that mushroom broth can be substituted for beef broth- it was delicious! Making it in the crock pot makes it so easy to make a big batch of this soup without much work.
Instead of using beef broth I use mushroom broth in this recipe. This is usually easy to find near Thanksgiving, but can be more challenging other times of the year. Lipton has a great mushroom and onion soup mix that most grocery stores sell in the soup aisle, I’ve found it works really well and gives the soup a great flavor.
3 pounds sweet yellow onions, sliced thin
3 tablespoons minced garlic
4 tablespoons butter
8 cups mushroom broth
1 loaf French bread, sliced
Place sliced onions, garlic and butter in the crock pot on low for 4-6 hours or until they are caramelized. I like to stir them every hour or so to make sure they are cooking evenly.
Once all the onions are caramelized, stir in the mushroom broth. Let the soup simmer for at least an hour on low to let all the flavors come together. You can also add in a teaspoon of dried thyme at this point, it adds a nice flavor to the finished soup.
Ladle soup into heat-safe bowls, top with bread and a slice of cheese of your choice. Broil for a few moments or until the cheese has melted on the bread.